Bone samples from the midshafts of the femur, tibia, fibula, humerus, radius and ulna and the middle third of the sixth rib are obtained from dissection room cadavers. The density of osteons and osteon fragments (number per unit area) is determined for each bone for each cadaver. The mean osteonal cross-sectional area is also determined for each bone. Both within and between individal comparisons are made so that differences in osteon density that characterize the various bones of the human skeleton can be identified, variability among individuals determined. A major goal of this project is to establish standards by which histomorphometric data from different skeletal sampling sites can be compared. Careful attention is also payed to health information available for each individual. Preliminary work has identified particular conditions that appear to alter the osteon density of an individual when they are compared to age-matched data. An additional goal of this project is to verify these data and identify possible other factors. The project also attempts to identify whether certain bones are more reactive to disease and other insults.